This is an expected behavior. This is due to the lack of memory that the system has, an example could be the i.MX8M-EVK where the memory is higher than the i.MX6 en the android oreo image runs well. Unfortunately, the only solution could be through hardware. I apologize for the inconveniences this could give you.

I don't think it's due to the lack of memory, I'm running a very simple example in imx yocto GA release, in such circumstances the total used memory is around 200MB only and my system has 2GB memory but this message still prints. I guess as CMA is a SHARED memory pool, there might be some bugs on memory management.